public class J02long {
    public static void main(String[] args) {
        long l1 = 21;
        long l2 = 2147483647;
        long l3 = 2147483648L;
        long l4 = 2147483648l;

        System.out.println("===float==");
        float f1 = 3.14f;
        float f2 = 3.14F;

        double d1 = 3.23;

        System.out.println("数据转换");
        System.out.println(d1);
        //字符串的拼接
        System.out.println("d1的值为：" + d1);
        //d1.sout
        System.out.println(d1);
        //d1.soutv
        System.out.println("d1 = " + d1);

        double d2 = 100.9;
        System.out.println("d2 = " + d2);

        System.out.println("自动转换");
        int num1 = 15;
        long num2 = 1000;
//        自动转换
//        num2 = num1;
//        System.out.println("num2 = " + num2);
//        num1 = num2;
        //强制转换，有风险
        num1 = (int)num2;
        System.out.println("num1 = " + num1);
        System.out.println("=======");
        byte b1 = 2;
        int i1 = 1000;
        b1 = (byte) i1;
        System.out.println("b1 = " + b1);
    }
}
